Test the XMLRPC interface to XWiki

We need functional tests for the XMLRPC classes. This is becoming more and more urgent as we have Xeclipse (another SOC project) using them.

I will write JUnit tests using the Apache XMLRPC client (http://ws.apache.org/xmlrpc/) to test against a real XWiki instance.

Since these functional tests will not use Selenium, the structure of the distribution-tests directory could be the following (proposed by vmassol):
distribution-tests/selenium-tests/
distribution-tests/xmlrpc-tests/
distribution-tests/some-other-kind-of-tests...

several pros:
1) you can the different types of tests separately
2) it's very clear where tests are located
3) we don't have test naming issues
4) we make way for other types of tests in the future